
How To Increase Water Hardness In Aquarium: 5 Easy Ways
· 2. Crushed coral. Maybe you've never heard of it, but crushed coral can be used to make your water harder. It has a high concentration of calcium carbonate and will raise the pH level in whatever aquarium is hosting it. You can either position your crushed coral in a media bag or mix it with gravel. When you add crushed coral to your water ...